Linus noticed that the new tick_dep_mask types introduced in:
d027d45d8a17 ("nohz: New tick dependency mask")
... are sloppily defined as 'unsigned long' - which is wasteful
to carry just 4 bits and which may also create suboptimal data
types on 64-bit systems with word alignment padding holes in them.
Fix this by changing the type to the more natural 'unsigned int'.
(The xchg_or() API will work fine with 'unsigned int' as well.)
Reported-by: Linus Torvalds <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Luiz Capitulino <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Viresh Kumar <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
include/linux/sched.h | 4 ++--
kernel/time/tick-sched.c | 11 +++++------
2 files changed, 7 insertions(+), 8 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c617ea12c6b7..6d1842bb7abd 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -718,7 +718,7 @@ struct signal_struct {
struct task_cputime cputime_expires;
#ifdef CONFIG_NO_HZ_FULL
- unsigned long tick_dep_mask;
+ unsigned int tick_dep_mask;
#endif
struct list_head cpu_timers[3];
@@ -1548,7 +1548,7 @@ struct task_struct {
#endif
#ifdef CONFIG_NO_HZ_FULL
- unsigned long tick_dep_mask;
+ unsigned int tick_dep_mask;
#endif
unsigned long nvcsw, nivcsw; /* context switch counts */
u64 start_time; /* monotonic time in nsec */
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 851631899352..fe0f57f3432f 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -157,9 +157,9 @@ static void tick_sched_handle(struct tick_sched *ts, struct
pt_regs *regs)
cpumask_var_t tick_nohz_full_mask;
cpumask_var_t housekeeping_mask;
bool tick_nohz_full_running;
-static unsigned long tick_dep_mask;
+static unsigned int tick_dep_mask;
-static void trace_tick_dependency(unsigned long dep)
+static void trace_tick_dependency(unsigned int dep)
{
if (dep & TICK_DEP_MASK_POSIX_TIMER) {
trace_tick_stop(0, TICK_DEP_MASK_POSIX_TIMER);
@@ -259,10 +259,9 @@ static void tick_nohz_full_kick_all(void)
preempt_enable();
}
-static void tick_nohz_dep_set_all(unsigned long *dep,
- enum tick_dep_bits bit)
+static void tick_nohz_dep_set_all(unsigned int *dep, enum tick_dep_bits bit)
{
- unsigned long prev;
+ unsigned int prev;
prev = xchg_or(dep, BIT_MASK(bit));
if (!prev)
@@ -289,7 +288,7 @@ void tick_nohz_dep_clear(enum tick_dep_bits bit)
*/
void tick_nohz_dep_set_cpu(int cpu, enum tick_dep_bits bit)
{
- unsigned long prev;
+ unsigned int prev;
struct tick_sched *ts;
ts = per_cpu_ptr(&tick_cpu_sched, cpu);
